Percorrer por autor "Conselheiro, Raul"
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- Structural and electrical characterization of dry electrodes for electrical stimulationPublication . Conselheiro, Raul; Leitão, Paulo; Agulhari, Cristiano MarcosWearables aimed at rehabilitation with signal monitoring and muscle stimulation support systems represent a great advancement toward an increase in the quality of health care. Common monitoring and stimulation usually use wet electrodes, but these have the problem of the gel dehydrating over time worsening the conductivity, then requiring the electrodes to be changed or verified frequently, increasing the workload of the professionals of the area. Other factors that increase the burden on them are the preparation, position, and connection of the electrodes since this usually requires specialized knowledge. To solve this issue, dry electrodes were developed and tested regarding endurance, signal acquisition quality, and electrical stimulation capabilities. The combinations of three substrates options, five different thin films, and three sizes were tested. Different connection methods were tested to enable the use of the electrodes with commercial standard connectors. Therefore, the goal of this work was to characterize the electrodes regarding signal acquisition quality, electrical stimulation, structural endurance, and connection stability. The electrodes were tested both in simulated environments as well as in vivo to better understand the influence of the body on them. The results show that with the current configuration, TiNCu0.45 in Polylactici Acid (PLA), employing snap button connector is the best choice although still requires some structural improvements to keep the conductivity. Polyurethane (PU) and Cellulose were discarded due to their mechanical properties. The other thin films presented high susceptibility towards corrosion, which greatly degraded conductivity.
- Titanium based dry electrodes for biostimulation and data acquisitionPublication . Conselheiro, Raul; Lopes, Claudia; Azevedo, Nelson; Leitao, Paulo; Agulhari, Cristiano; Veloso, H.; Vaz, F.; Gonçalves, João Lucas; Franco, Tiago; Oliveira, Leonardo Sestrem deWet electrodes rely on conductive electrolyte gel for proper perfor- mance, usually presenting high setup time and being disposable or requiring time-consuming cleaning methods. Skin irritation and signal quality deterioration are some of the problems that may occur with these electrodes. Therefore, to overcome these drawbacks, 3D printed bases using Fused Deposition Modelling (FDM) with Polylactic acid (PLA), Polyurethane (PU) and Cellulose filaments were functionalized with titanium (Ti) and titanium-nitride (TiN) thin films and dopped with copper (Cu). The electrodes, implemented using different diameters, were used to record electromyography (EMG) signals proceeded by biostimula- tion sessions to access their electrical and mechanical characteristics and com- pare them to that of commercial AgCl/Ag electrodes. The results show that TiN and TiNCu0.45 dry electrodes present results similar to wet AgCl/Ag electrodes for data acquisition. To be comparable to usual carbon electrodes for muscle stimulation, they need some conductivity improvements to lower the necessary voltage. Besides, the endurance of the thin films must be enhanced as well as the adhesion to the polymer.